April is the month when our gardens show off their best selves. Bulbs are blooming, annuals are showing off, native plants are lush and green, and summer’s vegetable seedlings promise future bounty.
gardens around you
Garden tours bound this month. Most benefit a local organization or garden club. You can find a listing at sandiegouniontribune.com/lifestyle/home-and-garden/story/2022-03-05/garden-tours.
Watch the hillsides. Native plants like California lilac (Ceanothus), climbing penstemon (Keckiella cordifolia), bush poppy (dendromecon rigida), cleveland sagesage clevelandii), red bush monkeyflower (Mimulus aurantiacus), island snapdragonGambelia speciosa) and many more bloom around this time. These wildland plants are suited to our home gardens, where their flowers support butterflies, bees, birds and other wildlife.
San Diego Botanic Garden, Balboa Park, the San Diego Zoo, and San Diego Zoo Safari Park are wonderful places to stroll and appreciate the gardens. Yes, the Zoo and Zoo Safari Park are better known for their animal collections, but their plants are pretty wonderful, too.
As you stroll, photograph the plants and gardens you like. Create a wish book for next fall, which is prime planting time. Share your images with other home gardeners in the San Diego Gardener Facebook group, facebook.com/groups/sdgardener/.
This is the best time to start your summer vegetable garden, from seed or from seedlings.
Have you struggled with starting seeds? Have your seedlings grown too long and leggy? Do they fall over soon after sprouting? Do they die when you move from a small pot to a large pot? Learn to grow lush, healthy seedlings without any of those failures in “Easy Seed Starting Workshop Online.” Enroll in the self-paced workshop at learn.waterwisegardener.com.
Plants to start now from seeds or plant as seedlings: pumpkin, summer squash, peppers, eggplants, cilantro, tomatillo, watermelon, zucchini and cucumbers. All these vegetables require six hours of full, direct sun each day.
Start from seed only: carrots, beets and other root crops. Root crops don’t transplant well.
There’s time for one more crop of beans, spinach, kale, dandelion greens and arugula before temperatures get too warm. Plant seeds or seedlings.
Starting a vegetable garden from scratch? Plan to grow vegetables in raised beds, not in the ground. Vegetables thrive in moist soils, high in organic matter and fertilized regularly. These conditions are far easier to create and maintain in raised beds than in the ground.
Build your own raised beds. Watch my video to see how to build and plant a raised bed: https://tinyurl.com/rsbed.
For prefabricated raised beds, look at Vegepod (https://tinyurl.com/vegpod), a great stand-alone bed system with built-in irrigation. These waist-high beds work amazingly well and are especially good for people who have back and knee issues. For in-ground beds, try coated metal Vego garden beds (https://tinyurl.com/vegogarden).
Before you plant, top off existing vegetable beds with layers of compost, earthworm castings, and granular organic vegetable fertilizer. Use a hand trowel to gently mix them into the top few inches of soil.
The best irrigation for raised beds is narrow in-line drip, such as Netafim Techline EZ, with emitters spaced every 6 inches. Shop for Netafim Techline EZ at your local irrigation store.
Set up cages for tomatoes and trellises for beans, cucumbers and other climbers before you plant. I make supports from sheets of concrete-reinforcing mesh, held together on the short ends with zip ties. Fold the mesh to create a freestanding cylinder, about 3 feet in diameter — perfect for two tomatoes, five or six cucumbers, 10 bean plants, and so on.
Rotate plantings of nightshade crops — tomato, pepper, eggplant, tomatillo — which are all susceptible to the same suite of soil pathogens, so when you plant them in the same soil year after year, they produce less and less. Start with two garden beds; plant all nightshades in one bed the first year. Move them to the other bed in the second year. Move them to the original bed in the third year and continue with that rotation.
Can adding fresh soil help a bed where tomatoes were attacked last year by root-knot nematode? Sadly, adding soil won’t stop root knot nematodes, a parasitic roundworm. The only way to stop them is by planting them elsewhere this year.
flowers and wildflowers
plant Zinnia from seed. The “Giant” series from Benary Seeds makes huge plants covered in huge flowers in fantastic colors. ‘Giant Lime’ blooms chartreuse green, ‘Giant Wine’ blooms bright burgundy, ‘Giant Yellow’ blooms golden yellow, and so on. As flowers start to fade, deadhead frequently to encourage new buds and blooms.
Pick garden flowers to enjoy indoors and outdoors, too. Pick your own flowers, not your neighbors’ and NEVER plants or flowers from native habitats or public landscapes. If it doesn’t belong to you, don’t cut it and don’t pick it.
Cut back California poppy plants after their first blooms fade. Water and wait. They’ll sprout a new set of leaves and bloom again.
Cut sweet pea flowers to make bouquets. The more flowers you cut, the more you get. And their flowery perfume will fill your home!
Epiphyllum, also known as orchid cacti, start blooming now. Their big, multilayered flowers look like colored cellophane. The plants are very easy to grow and propagate. If you have a friend who has one you like, ask for a cutting — cut sections apart at the joints — then root in a mixture of potting soil and small redwood bark. Epiphyllum are best as hanging plants, with morning sun exposure or under dappled shade.
Ornamental trees, vines and shrubs
Along the coast, continue to plant ornamental trees, vines and shrubs.
Plant any kind of succulent now, from tiny red, gold and orange pork and beans sedum to giant, coral-flowered tree Aloe. Native liveforevers (dudleya species) plants are silvery bladed succulents, mostly rosette-shaped that are fantastic especially in rock gardens.
While you might be attracted to fine, soft-textured plants, too many of those plants are chaotic without the contrast of broad-leaved and succulent plants. Combine the two for the most beautiful garden beds.
lemongrass (Cymbopogon citratus) is a tall, bright-green grass with half-inch-wide blades that form handsome mounds. Plant in full sun, in a moderately irrigated bed. Harvest by cutting the stalks at the base. Thinly slice the tender, pale green portions to use in Thai curries. Steep the stems and leaves for hot or iced tea.
Oregano and sage both make excellent low-growing, low-water ground covers. Sample varieties, then choose your favourite.
Plant a big pot of basil outside the kitchen door so you can pick it to use while you cook.
If you have a sun-filled balcony, patio or porch, grow dwarf varieties of tomatoes, peppers, eggplants and more in containers. Choose unglazed terra cotta over glazed ceramic.
If you plant black plastic nursery pots, drape them in light-colored fabric in the heat of summer, so the intense sunlight doesn’t heat the pot and cook the roots.
Match the pot to the plants:
- A 15-gallon black nursery pot has room for ONE tomato plant or TWO pepper plants or eggplant plants or basil plants.
- A half whiskey barrel or wine barrel has room for two tomatoes or three peppers, or three eggplant plants, or three basil plants. Alternatively, plant three cucumber plants or one squash plant or five cilantro plants.
Geotextile fabric pots are easy to use but dry out superfast in our climate. In summer, water daily to keep the soil moist so plants don’t wilt.
Whatever pot you use, fill it with high quality potting mix. Don’t skimp.
Plant citrus, guava, banana and other heat-lovers now. Group these thirsty plants together so they can be watered well without overwatering the rest of the garden.
Thin the marble-size fruits on nectarines, apricots and other deciduous fruit trees to one fruit per 4 to 6 inches along each branch. Compost the thinned fruits.
Remove fruits from newly planted trees so they put their energy into strong roots and leaves instead. Those roots and leaves will support future crops.
Feed stone fruits, apples and other deciduous fruit trees with organic fruit tree fertilizer. Follow label directions.
Water fruit trees often enough to keep the soil slightly damp.
DO NOT rototill. Today, we know that rototilling destroys soil structure and disrupts the critically important community of beneficial microbes that live in the soil and interact with plant roots. Rototilling also destroys earthworm habitat and causes soil to compact once it resettles — the opposite of its intent.
Turn over potted bromeliads and shake out the standing water in their “tanks.” Turn back upright and sprinkle Mosquito Bits into the center when you refill it. Mosquito Bits contain the biological pesticide Bt, which kills worms, caterpillars (so be careful with it around pollinator plants) and mosquito larvae.
Keep up with weeds! Grab a hoe or get down on your hands and knees to pull weeds out by the root. Don’t bother spraying. By the time sprayed weeds die, they will have flowered and made seeds that rest in the soil to sprout next year. And besides, sprays aren’t good for the environment.
Adding thick mulch over garden beds keeps dormant weed seeds from sprouting.
Inspect your irrigation system. Turn on each zone to check for leaks and breaks, flush each drip irrigation zone. Convert spray and old-fashioned drip to in-line drip.
Avoid breeding mosquitoes; empty all bowls, dishes, buckets and anything else that holds standing water. Decommission old fountains and plant them with succulents instead.
Remember to wear sunscreen, long sleeves and a hat outdoors. While the sun might feel nice on your skin, those UV rays are damaging. Protect yourself and drink lots of water.
Sterman is a waterwise garden designer and writer and the host of “A Growing Passion” on KPBS television. More information is at growingpassion.com and waterwisegardener.com.